Solid end mills, especially with cutting diameters equal and larger than 12 mm, implemented with currently well-known straight and eccentric clearances (or combination of both), when applied to cutting metals, tend to generate, sometimes considerable, vibrations (or chatter). Suppressing vibrations is one of most essential requirements to any solid end mill. Therefore, there is a huge effort to develop and pro-duce special geometry features helping to reduce or eliminate chatter.
By implementing end mills with an unequal index, deferential helix angles, veritable helix angles, and the like, the problem partially gets solved. For example, some of these features might work well for titanium alloys, but does not suppress vibrations in stainless steels, or other materials. In addition, some combinations of these features provide an acceptable solution for cutting diameters up to 12 mm, but vibrations still exist at larger cutting diameters.
The so-called “micro land” is the currently existing solution to suppress vibrations for solid end mills with a cutting diameter larger than 12 mm, which is produced by grinding a tiny clearance facet of 0.05-0.1 mm width and with an angle of between 1.5-3°. The clearance facet must be ground adjacent the cutting edge. Along with high accuracy needed for grinding the land width and angles, the “micro land” requires, at least two cleanses (i.e., minimum 2 passes) on each tooth, and probably three cleanses for each tooth.
Another problem is that cutters with the “micro-land” consume considerably larger spindle power vs. cutters without the “micro-land.” In fact, there is an increase in specific energy, which in turn produces larger hit generation during milling, which in turn creates additional difficulties in applying cutters with the “micro-land” to cut high temperature alloys. In view of the foregoing, improved end mills are de-sired that provide one or more advantages over conventional designs.